There is not a single "inertial" reference frame, there are many. And Einstein suggested that any inertial frame is just as valid as any other inertial frame.

If you take two observers in two different inertial frames, they may disagree about how long things took, or in what order they occurred, if they occurred in different places. So some observers may see the two objects being dropped at the same instant, while others with think one (or the other) dropped first. Similarly, some observers will think that one (or the other) hit the ground first.

There is not a single "inertial" reference frame, there are many. And Einstein suggested that any inertial frame is just as valid as any other inertial frame.

If you take two observers in two different inertial frames, they may disagree about how long things took, or in what order they occurred, if they occurred in different places. So some observers may see the two objects being dropped at the same instant, while others with think one (or the other) dropped first. Similarly, some observers will think that one (or the other) hit the ground first.

Einstein says it doesn't matter. Time is all relative anyway. Get over it.

While I associate myself with the twins paradox , can you please explain how the ground is able to apply opposite direction to gravity and push back according to Newtons third law?

The ground is clearly travelling the same direction has the object and it is surely the object imposes a force on the ground and gravity imposes a force on the ground. The ground is not capable of pushing back it is only capable of density which is the resistance to ''falling'', when are we ever not falling?

Ok I have read enough of the twin Paradox to realise there is no Paradox.

The twin leaves earth at 0t , he returns at 0t , why he was gone they were counting, none of them managed to count at the same rate causing an imaginary age difference. They aged the same but the numbers showed a different because they did not have a constant counting system.

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